The probe card is a tool for testing semiconductors used at “Wafer Test” to check quality of IC or LSI in the first process of semiconductor manufacturing. In the manufacturing process of semiconductors such as IC and LSI, “Wafer Test” utilizing probe cards is performed to check quality of IC chips, so that the process yield can be increased effectively since defects can be screened to be repaired or discarded. Generally, a good probe card can raise yield of a semiconductor manufacturing process for about 20% and thereby reduce the cost thereof.
As semiconductor manufacturers continue to shrink die geometries, which makes the task of on-wafer testing increasingly more difficult, probe card with innovative solutions are required to meet the semiconductor industry's test needs so as to ensure higher accuracy and repeatable wafer testing and thus increase yield. According to an investigation made by VLSI Research, Inc, as the recovery of probe card industry following the revive of world economy, the revenue growth of the probe card industry surpasses that of the semiconductor industry in Year 2004, that its celebrated with a 42% growth with annual revenue as high as 683.6 million U.S. dollars. Moreover, as the popularization of flip chip package process, the compound annual growth rate of gold bump and solder bump is 25% and higher that it is anticipated that the needs for vertical probe is going to increase year by year.
The vertical probe head currently used is originated from a manufacturing process disclosed at 1997 in U.S. Pat. No. 4,027,925, wherein a vertical probe head disclosed has each of it's probes buckle or deflect when a predetermined axial load is applied thereto for enabling the same force to be exerted on each of a plurality of pads on a semiconductor chip as it is being tested. Moreover, each guide plate of such vertical head is processed by a mechanical drilling means for forming holes thereon while enabling each hole to be formed at a position corresponding to a pad to be tested on the semiconductor, such that a probe head can be completed as each hole is fitted with a probe manually. However, it is noted that the probes of the aforesaid manufacturing process require to be process by a one-by-one manner that is, not only time-consuming, but also the geometrical shape an the precision of each probe are limited as the cross-section of each probe is a circular shape. Furthermore, as the holes used to receive and fix probe of the guide plate are formed by a mechanical drilling means, the pitches between holes can not satisfy the precision requirement of smaller than 120 μm.
Further, as the techniques disclosed in U.S. Pat. Nos. 6,927,586 and 6,906,540, a probe having various geometrical-shaped cross-sections is manufactured by a means of chemical etching. However, the material that can be used to make such probe is limited to be Beryllium Copper (BeCu). Moreover, the holes used to receive and fix probe of the guide plate are still formed by a mechanical process so that the number of probes to be arranged on a unit area can not increase since the pitches still can not be reduced.
In addition, In T.W. Pat. No. 569017, entitled “a vertical probe card with force feedback”, a method of utilizing a MEMS (micro-electro-mechanical system) process to manufacture multi-layer probes is disclosed. Although the method of manufacturing multi-layer probes is advantageous mass production, the precision of probes formed thereby are reduced since the error of flatness of each layer is accumulated to the next layer firmed successively thereafter as the multi-layer probes are formed by a process of stacking a layer on top of another. It is noted that the accumulated error is going to adversely affect the assembly of such multi-layer probes to its guide plate as the holes are not aligned properly, and thus affect a test precision as it is being used to test a semiconductor chip.
Therefore, it is in need of a novel vertical probe head capable of overcoming the shortcomings of those prior-art probes.